Objective
Low serum vitamin D levels have been associated with increased prevalence of the reproductive tract condition bacterial vaginosis (BV). The objective of this trial was to evaluate the effect of high-dose vitamin D supplementation on BV recurrence.

Results
Participants were primarily African-American (74%), with a median age of 26 years. Median pre-supplementation serum vitamin D (25(OH)D) was similar across randomization arms: 16.6 ng/mL in the vitamin D arm and 15.8 ng/mL in the control arm. At trial completion, median 25(OH)D among women receiving vitamin D was 30.5 ng/mL, vs. 17.8 ng/mL in control women; 16% of women receiving vitamin D and 57% receiving placebo remained vitamin D deficient (<20 ng/mL). BV recurrence was not reduced by vitamin D supplementation (intention-to-treat hazard ratio: 1.11 (95% confidence interval: 0.68, 1.81). By the 24-week visit, 65% of women randomized to vitamin D had BV, compared to 48% of control women. Median time to BV recurrence was 13.7 weeks in the vitamin D arm and 14.3 weeks in the control arm.